Neuromodulation for evaluating the pathophysiology of migraine

The two most frequently used techniques for the non-invasive modulation of brain activity are repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS). These techniques have repeatedly been used to modulate the activity of a given area within a neuronal network to study pathophysiological changes in migraine. The most freqeuntly stimulated areas are visual and sensorimotor areas. We discuss here what kinds of paradoxical effects have been described in response to inhibitory and excitatory modulation in patients with episodic and chronic migraine and how neuromodulation can help distinguish patients with chronic migraine from those with medication overuse headache. Furthermore, we elaborate how these methods can normalize the habituation deficit in response to visual and somatosensory stimuli, frequently detected between migraine attacks. From the studies reviewed in this chapter, it emerges that the brain of the migraine patient is characterized by alterations of synaptic activity-dependent plasticity, i.e., the phenomena of long-term potentiation and depression.